Bostonians elected an African-American woman and an Asian-American woman to two of four at-large City Council seats in a dramatic leadership change at City Hall, according to unofficial election results.

As poll numbers rolled in Tuesday night, Ayanna Pressley and newcomer Michelle Wu topped the ticket. Michael Flaherty, a former mayoral and council candidate, also secured a seat, finishing third, along with Council President Stephen J. Murphy, who finished fourth.

With all precincts reporting in the at-large council race, Pressley was ahead with 18.3 percent of the vote, compared with Wu’s 17.98 percent, according to unofficial figures from the Boston Elections Commission.

Pressley, a Dorchester resident, had championed lifting families out of crisis and improving the lives of women and girls. She had also sought to ease the liquor licensing process to get more entrepreneurs to open restaurants in poorer neighborhoods.

Wu, a 28-year-old lawyer whose parents are Taiwanese immigrants, said she wanted to lift barriers between families and city government.Wu and other councilors said they were bouyed by a higher-than-expected turnout.

“I am thrilled, I am exhausted, and all at the same time,’’ said Wu, of the South End.“It’s really been a long day, a long eight months. But I couldn’t be happier to be in the top four.”

Flaherty said he is heartened that voters returned him to the council, adding that the issues he championed, such as better schools and safer streets, resonated with residents. As a former Boston city councilor, he said he had an advantage.

“I am a familiar face,’’ said Flaherty, who resigned from the council in 2009 to run for mayor. “People know me. they know my work ethic. They know my experience.”

With so many council slots open, the campaign had been framed as a new opportunity to change the balance of power between the new mayor and the council. Under Menino, the council had been seen as a weak legislative body that did little to challenge the mayor.

Though it does serve as a bully pulpit, the council’s sole authority is to approve the budget the mayor submits. Critics had slammed members for dragging their feet on a vote on a hefty police contract.

Among a large field of men, four women competed, including Suzanne Lee, a former school principal born in China who on Tuesday lost a fierce challenge to Councilor Bill Linehan in District 2, which includes South Boston, Chinatown, and the South End.

The last time both competed, in 2011, Linehan won by just 97 votes. But with 100 percent of precincts reporting Tuesday night, Linehan had won 52.88 percent of votes, compared with Lee’s 46.79, the Election Commission said.

“This was a hard-fought race, but I’m thrilled to be able to keep working on behalf of my constituents to ensure their needs are met on a daily basis as our great city continues to prosper,’’ said Linehan, who declared victory about an hour after polls closed at 8 p.m.

The Lee-Linehan bout proved to be scrappy and contentious at times. Last week, Linehan demanded an apology from Lee for an ad her campaign sent to voters, calling it “shameful.” Lee later defended the ad, saying it included quotations published in local newspapers. But her statement turned off some voters.

Another woman in the race,Boston teacher Annissa Essaibi-George, also lost her council bid. Essaibi-George, a small-business owner and a mother of four boys, placed fifth Tuesday night. She had championed improving public safety and fixing the high schools.

She had supported a hefty police contract.

In council history, the highest number of women elected was in 1994, when Peggy Davis-Mullen, Maura Hennigan, Diane Modica, and Maureen Feeney were elected. Prior to 1994, no more than two women had served on the council at one time. Pressley has been the only women for the past two years.